Practical_Antenna_Handbook_0071639586

I n d e x 757
noise (Cont.):
sky noise, 494–495, 498
solar, 49
noise bridge, 592–598
noise factor (F n ), 492–493
noise figure (NF), 492–494
noise temperature (T e ), 493–495
nonresonant longwire, 256–258
nonresonant loop, 365–366
nonresonant rhombic, 260, 262
nonresonant vee beam, 260, 261
normalized impedance, 559–562, 574
northern lights, 75–76
nulls (loop antenna), 342–346, 359
Numerical Electromagnetic Computation
(NEC) program, 546
O
off-Âcenter-Âfed dipole, 225–226
ohm (Ω unit of resistance), 82–83
ohmic loss, 28, 107, 178, 447, 449, 473
ohmmeter (coaxial cable test), 615–616
Ohm’s law, 82–83, 686
in transmission lines, 125
omega (Ω), 115, 715
omega-Âmatch feed systems, 244–246
omnidirectional, 265–266
1λ loops, 209–216
open-Âwire line (OWL), 110–111, 687, 689
ordinances, 701
Orr, William, Âex-ÂW6SAI, 277
OSCAR satellite communications, 6
oscilloscope, 127–131, 712
(See also transmission lines)
P
parabolic (dish) antennas, 481–485
beamwidth, 483
Cassegrain feed, 483–484
directrix, 481–482
effective aperture, 483
feed geometries for, 483–485
gain, 483
monopulse feed, 483, 485
parallel conductor lines 110–111
(See also Âopen-Âwire line)
parasitic arrays, 161–162, 277, 280–282, 419
path loss, 18
pedestal (tower), 669–671
pennant antenna, 359–360
period (T; of a waveform), 712, 715
permeability (µ), 90, 116, 460
relative (µ r ), 90
permittivity (ε; dielectric constant), 88, 105,
116–118, 460
relative (ε r ), 88
phase, 91, 100, 150
phase constant (β), 120, 140–142
phase-Âcontrol circuit, 340–341
phase-Âlocked receivers, 68
phase-Âshift networks, 156, 267–271, 485–487
phase velocity (V p ), 455–458
phasing, 149–153, 158–159, 266, 273, 340–341
physical vs. electrical length, 105, 140, 176–177
pi network, 537
“picket fencing,” 32
planar loop windings, 345
planetary terminator (See gray line
propagation)
planning board, 702–703
“plumbers’ delight” Yagi, 277
polarity, 82, 88, 99, 104
polarization, 18–19, 229, 473
polarization diversity, 67–68, 331–332
Popov, Alexander, 3
pop rivets, 290, 296
power (P), 83
(See also effective radiated power)
power density, 16–17, 471–472
power distribution, 683, 689–690
power gain (G p ), 477–478, 710–711
preamplifier for receiving antennas, 355–356
PRB-1 (FCC), 700
predictions, propagation, 76–79
propagation constant (β), 462
propagation modes in waveguides, 451–454
propagation of radio waves, 9–79
ducting, 39–40, 42
fading, 41–42
ground wave, 27–38
ionospheric (see ionospheric propagation)
inversion, 39
line of sight, 28
medium, 12–13
meteor scatter, 76
path types, 26–27
radio horizon, 32, 39
subrefraction, 40